1. Technical Field
The present application relates to a light-emitting diode element and relates to a high-output light-emitting diode element.
2. Description of the Related Art
A nitride semiconductor including nitrogen (N) as a Group V element is a prime candidate for a material to make a short-wave light-emitting element because its bandgap is sufficiently wide. Among other things, gallium nitride-based compound semiconductors (which will be referred to herein as “GaN-based semiconductors”) have been researched and developed particularly extensively. As a result, blue light-emitting diode (LED) elements, green light-emitting diode elements, and semiconductor laser diodes formed of GaN-based semiconductors have already been used in actual products (See, for example, Japanese Laid-Open Patent Publications No. 2001-308462 and No. 2003-332697).
Light-emitting diode elements commercially available in the present market are manufactured by epitaxially growing a GaN-based semiconductor layer, such as GaN, InGaN, and AlGaN, on a c-plane substrate, and the light-emitting diode element (LED chip) is mounted to a submount. The planar size of a light-emitting diode element (the planar size of the principal surface of the substrate: hereinafter, simply referred to as “chip size”) varies depending on the use of the light-emitting diode element. Typical chip size is, for example, 300 μm×300 μm or 1 mm×1 mm.
The arrangement of the electrodes of the light-emitting diode element can be roughly divided into two types. One is the “two-sided electrode type” wherein the p-side electrode and the n-side electrode are provided on the front surface and the rear surface, respectively, of the light-emitting diode element. The other one is the “one-sided electrode type” wherein both the p-side electrode and the n-side electrode are provided on the front surface of the light-emitting diode element.
WO 2011/010436 discloses a light-emitting diode element as described hereinbelow (See FIG. 18 included in WO 2011/010436). The light-emitting diode disclosed in WO 2011/010436 includes an n-type conductive layer 2 formed of a gallium nitride-based compound, a semiconductor multilayer structure 21 which includes a p-type conductive layer 4 and an active layer 3, a p-side electrode 5 provided on the p-type conductive layer 4, a conductor portion 9, and an n-type surface electrode 6. The n-type conductive layer 2 has a principal surface of an m-plane and a rear surface. The semiconductor multilayer structure 21 is provided in a first region 2a of the principal surface of the n-type conductive layer 2. The active layer 3 is interposed between the n-type conductive layer 2 and the p-type conductive layer 4. The conductor portion 9 is provided in a second region 2b of the principal surface of the n-type conductive layer 2. The conductor portion 9 is in contact with an inner wall of a through hole 8. The n-type surface electrode 6 is provided in the second region 2b of the principal surface of the n-type conductive layer 2. The n-type surface electrode 6 is in contact with the conductor portion 9.
Japanese Laid-Open Patent Publication No. 2012-124330 discloses a semiconductor light-emitting element including a semiconductor film which includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer, an n-side electrode provided on an exposed surface of the n-type semiconductor layer, and a p-side electrode provided on a surface of the p-type semiconductor layer. The exposed surface is formed by partially removing the semiconductor film from a surface of the p-type semiconductor layer. According to Japanese Laid-Open Patent Publication No. 2012-124330, the semiconductor light-emitting element has a current guiding portion which is lying on or inside the n-type semiconductor layer and lying above the p-side electrode and which has a higher electrical conductivity than the electrical conductivity of the n-type semiconductor layer.